J
John Larkin
Guest
On Fri, 23 Jun 2023 13:31:45 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
Here\'s a few pic from my hike.
https://www.dropbox.com/sh/rh900ikkos51hnp/AAC4katl4FbYi7l76MYmXBTUa?dl=0
What\'s scary is that a lot of these hillsides slid, and trees tumbled
down, in our recent rains.
Our house is on a pretty steep hill, but it\'s dug into the rock, not
on skinny stilts.
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Friday, June 23, 2023 at 3:17:30?PM UTC-4, John Larkin wrote:
On Fri, 23 Jun 2023 11:43:19 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
On Friday, June 23, 2023 at 11:40:24?AM UTC-4, John Larkin wrote:
On Fri, 23 Jun 2023 00:21:10 -0700 (PDT), John Walliker
jrwal...@gmail.com> wrote:
On Friday, 23 June 2023 at 05:52:46 UTC+1, Ricky wrote:
On Thursday, June 22, 2023 at 8:27:25?PM UTC-4, Fred Bloggs wrote:
On Thursday, June 22, 2023 at 7:55:54?PM UTC-4, John Larkin wrote:
On Thu, 22 Jun 2023 15:50:24 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:
The people who designed and tested the hull knew what they were doing. A spontaneous implosion seems unlikely. What is not unlikely is a desperate and panicked crew banging something against the hull to make noise. If you start a fracture submerged in 6000 psi water, it\'s gone in a flash. Going to be impossible to conduct a forensics.
\" The company is working with NASAs Marshall Space Flight Center in Alabama on development and manufacturing.\"- may not apply to the Titan.
\"But last year [2019], tests determined that Titans pressure vessel could not be certified for that depth [4,000m].\"
\"As part of the Titan underwater testing program, the OceanGate team conducted a series of driverless diving tests. Gradually reduce the submersible to 4000 meters while using another strain gauge, viewport displacement sensor and custom designed acoustic sensor system to measure the health of the hull, providing analysis data during the submersible dive and between the two processes. . Many of these sensors will be permanently stored in the submersible\'s auxiliary device and will give the driver real-time feedback on the hull behavior of all future manned submersibles.\"- Chief engineer had a problem with so-called acoustic sensor system and was fired.
\"Future manned submersibles\" from these idiots sounds unlikely. They
should have tested it to 8000 meters.
\"Designed and manufactured by OceanGate, the Titan is made up of carbon fiber and titanium alloy and is the world\'s largest submersible of the same type. \"
Was.
https://www.geekwire.com/2020/oceangate-picks-toray-cma-make-carbon-fiber-titanic-worthy-submersibles/
https://www.lfrt-plastic.com/news/carbon-fiber-assists-the-us-manned-submersible-16233802.html
I\'d expect that carbon fiber is strong in tension, which is what a
pressurized airplane or a hydrogen tank needs. But in compression? You
seem the same effect in wood, stronger in tension than compression
because it can buckle.
And how does fiber in tension resist a force perpendicular to its surface. Reports say it\'s 5 inches thick.
That\'s just basic statics. Read a sophomore text book on the topic. They should have a good example of analyzing an I-beam. > Same concept.
Perhaps closer to the real situation there is plenty of analysis of Euler instability
in cylindrical structures. For example:
https://core.ac.uk/download/pdf/41167884.pdf
John
That\'s loading on a long solid cylinder. The more likely failure mode
of the sub was radial collapse of a long, relatively thin-wall hollow
cylinder from external pressure.
We just had a deck rebuilt. One side is tied to a header on the house
and the two outside corners are supported by long 4x4 wood posts. The
failure mode of the posts would be buckling, so I researched that.
How high up in the air is that thing that you should be concerned with \"buckling\"??? A 4 ft 4x4 spf is good for over 14,000 lbs compression. That drops to less than 4,000 lbs for a 10 ft length. The 10 ft post as a structural element just looks funny. There\'s a document called the National Design Specification that shows how to make things like composite structures such as using 4x4 to make an 8x8 column, in a structurally sound way. Wood is an imperfect material, so moments develop internally to create bending, warping and failing.
The deck might weigh 1000 lbs (1100 with my skinny wife) and each post
gets about 1/4 of that.
The 4x4s are about 12 feet long, but they pass through a lower deck,
which should supress buckling. The span between decks is 7 feet.
Should be fine.
There\'s a giant steel bracket at each top end, which will resist
twisting forces associated with buckling, even better.
The real hazard with decks is rot, and these are pressure-treated, not
sitting in dirt or anything.
There are houses around here, on steep hillsides, that are supported
by insanely long skinny posts on the downhill side. It\'s terrifying in
earthquake country. I\'ll take some pics next hike in the canyon.
Most of the deaths in our 1989 earthquake were the upper-deck
collapsed freeway in Oakland. It had won architectural awards for the
delicacy of the concrete supports.
Those 4x4\'s aren\'t even going to know they\'re loaded.
If it\'s a permitted job by a licensed contractor then it\'s totally code compliant and shouldn\'t be a problem.
That doesn\'t mean it will be pretty. Several thousand years ago the Greeks discovered an optical illusion when viewing their columns from a distance. And that is the center appears skinny relative to the ends. They overcame this by fattening them up in the middle, and the technique has been used ever since.
Here\'s a few pic from my hike.
https://www.dropbox.com/sh/rh900ikkos51hnp/AAC4katl4FbYi7l76MYmXBTUa?dl=0
What\'s scary is that a lot of these hillsides slid, and trees tumbled
down, in our recent rains.
Our house is on a pretty steep hill, but it\'s dug into the rock, not
on skinny stilts.